The patents to Edwards, U.S. Pat. Nos. 3,686,893; 3,913,351; and 3,977,852 describe cooling systems which operate on the reverse Brayton cycle. In conventional rotary vane reverse Brayton cycle refrigeration systems, air is supplied to the compressor portion of a sliding vane rotary air cycle device wherein the air undergoes isentropic compression. The air then passes through a heat exchanger wherein it undergoes a constant pressure cooling. The high pressure air then passes to the expander portion of the rotary air cycle device wherein it undergoes a reversible expansion after which it passes through a second heat exchanger wherein it picks up heat at a constant pressure.
In these systems the air must pass through inlet and outlet ports in the rotary air cycle device thereby increasing the losses in the system.